Merge pull request #13180 from esajaa/master

Update mbed-coap to version 5.1.6

Author: 0xc0170

features/frameworks/mbed-coap/CHANGELOG.md

@@ -1,5 +1,11 @@
 # Change Log
 
+## [v5.1.6](https://github.com/ARMmbed/mbed-coap/releases/tag/v5.1.6)
+
+- Multiple fixes for out-ouf-bounds memory accesses, a memory leak and an infinite loop condition in packet parser.
+- Mapped `MBED_CONF_MBED_CLIENT_RECONNECTION_COUNT` Pelion Device Management Client configuration option to `SN_COAP_RESENDING_MAX_COUNT` in mbed-coap.
+- Fix the token from blockwise ACK message to be empty if the received message doesn't have one.
+
 ## [v5.1.5](https://github.com/ARMmbed/mbed-coap/releases/tag/v5.1.5)
 
 - Added handling for duplicate message handling for Block2 messages. Previously CoAP was silently ignoring the duplicate messages. Now proper response will be sent.

features/frameworks/mbed-coap/mbed-coap/sn_config.h

@@ -165,6 +165,10 @@
  * \brief Defines how many times CoAP library tries to re-send the CoAP packet.
  * By default value is 3.
  */
+#ifdef MBED_CONF_MBED_CLIENT_RECONNECTION_COUNT
+#define SN_COAP_RESENDING_MAX_COUNT MBED_CONF_MBED_CLIENT_RECONNECTION_COUNT
+#endif
+
 #ifndef SN_COAP_RESENDING_MAX_COUNT
 #define SN_COAP_RESENDING_MAX_COUNT                     3
 #endif